The world's 15 biggest metropolitan areas

The world's 15 biggest metropolitan areas

"Half of humanity now lives in cities and within two decades, nearly 60 per cent of the world's people will be urban dwellers," according to a UN Habitat study.

As cities expand into mega regions, there is a rapid growth in the population as well. Some of the world's richest cities are also the most populous.

A report by McKinsey Global Institute says that India will have 68 cities by 2030 with a population of over 1 million, 13 cities with more than 4 million people, and 6 megacities with populations of 10 million or more.

Here's a list of the world's 15 biggest metropolitan areas, according to Allianz Knowledge.

1. Tokyo (Japan)

Metropolitan area: 35.2 million peopleCity: 12.9 million people

Tokyo, capital city of Japan is the most populous metropolitan area and the world's largest metropolitan economy with a GDP of $1.479 trillion at purchasing power parity in 2008.

The world's 15 biggest metropolitan areas

One of the fastest growing cities in the world, the capital city of India focuses on industrial sectors like information technology, telecommunications, hotels, banking, media and tourism. It contributes 4.94 per cent to India's GDP.